Soil Fungal Diversity of the Aguarongo Andean Forest (Ecuador)

Fungi represent an essential component of ecosystems, functioning as decomposers and biotrophs, and they are one of the most diverse groups of Eukarya. In the tropics, many species are unknown. In this work, high-throughput DNA sequencing was used to discover the biodiversity of soil fungi in the Aguarongo forest reserve, one of the richest biodiversity hotspots in Ecuador. The rDNA metabarcoding analysis revealed the presence of seven phyla: Ascomycota, Basidiomycota, Mortierellomycota, Mucoromycota, Glomeromycota, Chytridiomycota, and Monoblepharomycota. A total of 440 identified species were recorded. They mainly belonged to Ascomycota (263) and Basidiomycota (127). In Mortierellomycota, 12 species were recorded, among which Podila verticillata is extremely frequent and represents the dominant species in the entire mycobiota of Aguarongo. The present research provides the first account of the entire soil mycobiota in the Aguarongo forest, where many fungal species exist that have strong application potential in agriculture, bioremediation, chemical, and the food industry. The Aguarongo forest hides a huge number of unknown fungal species that could be assessed, and its protection is of the utmost importance.

Exophiala pseudooligosperma sp. nov., a novel black yeast from soil in southern China

Exophiala is an important genus, with several species associated with infections in humans and animals. In a survey of soil fungal diversity in Yunnan province, PR China, a novel taxon, Exophiala pseudooligosperma sp. nov., was identified based on combined morphological and molecular phylogenetic features. Morphologically, this species is characterized by having torulose, septate hyphae and swollen, terminal or intercalary conidiogenous cells arising at acute angles from aerial hyphae. Phylogenetic analysis of the combined sequences of the internal transcribed spacer, the small and large nuclear subunit of the rRNA gene and part of the β-tubulin gene confirmed the phylogenetic position of the new species within the genus Exophiala.

Small-scale variation in a pristine montane cloud forest: evidence on high soil fungal diversity and biogeochemical heterogeneity

Montane cloud forests are fragile biodiversity hotspots. To attain their conservation, disentangling diversity patterns at all levels of ecosystem organization is mandatory. Biotic communities are regularly structured by environmental factors even at small spatial scales. However, studies at this scale have received less attention with respect to larger macroscale explorations, hampering the robust view of ecosystem functioning. In this sense, fungal small-scale processes remain poorly understood in montane cloud forests, despite their relevance. Herein, we analyzed soil fungal diversity and ecological patterns at the small-scale (within a 10 m triangular transect) in a pristine montane cloud forest of Mexico, using ITS rRNA gene amplicon Illumina sequencing and biogeochemical profiling. We detected a taxonomically and functionally diverse fungal community, dominated by few taxa and a large majority of rare species (81%). Undefined saprotrophs represented the most abundant trophic guild. Moreover, soil biogeochemical data showed an environmentally heterogeneous setting with patchy clustering, where enzymatic activities suggest distinctive small-scale soil patterns. Our results revealed that in this system, deterministic processes largely drive the assemblage of fungal communities at the small-scale, through multifactorial environmental filtering.

Peach-Morchella intercropping mode affects soil properties and fungal composition

Objective This study aims to explore a three-dimensional planting mode in orchards and provide theoretical basis for the efficient peach-Morchella planting and soil management after Morchella cultivation. Methods Next-generation sequencing was performed to investigate the variations in soil physicochemical properties, enzyme activities and fungal composition under peach-Morchella intercropping for one year and two years, by using the soil without peach-Morchella intercropping as the control group. Results Peach-Morchella intercropping decreased the soil bulk density, and significantly increased the maximum field capacity, non-capillary porosity and total porosity, organic matter, available potassium and available zinc, which together improved soil structure and soil fertility. Besides, the intercropping mode obviously enhanced soil enzyme activities and mineral absorption and transformation in peach orchard soils. The intercropping also resulted in a decline of soil fungal diversity, and the 2-year soil samples were of higher abundance of Zygomycota. More importantly, peach-Morchella intercropping elevated the yields of both peach and Morchella, bringing about obviously higher economic benefits. Conclusion Continuous peach-Morchella intercropping improves the soil structure and fertility while decreases soil fungal diversity, which can contribute to greater economic benefits of the peach orchard. Our findings shed new light on the intercropping-fungus-soil relationship, and may facilitate the further development of peach-Morchella intercropping.

Cover Cropping Impacts Soil Microbial Communities and Functions in Mango Orchards

Soil microbes play critical roles in nutrient cycling, net primary production, food safety, and climate change in terrestrial ecosystems, yet their responses to cover cropping in agroforestry ecosystems remain unknown. Here, we conducted a field experiment to assess how changes in cover cropping with sown grass strips affect the fruit yields and quality, community composition, and diversity of soil microbial taxa in a mango orchard. The results showed that two-year cover cropping increased mango fruit yields and the contents of soluble solids. Cover cropping enhanced soil fungal diversity rather than soil bacterial diversity. Although cover cropping had no significant effects on soil bacterial diversity, it significantly influenced soil bacterial community compositions. These variations in the structures of soil fungal and bacterial communities were largely driven by soil nitrogen, which positively or negatively affected the relative abundance of both bacterial and fungal taxa. Cover cropping also altered fungal guilds, which enhanced the proportion of pathotrophic fungi and decreased saprotrophic fungi. The increase in fungal diversity and alterations in fungal guilds might be the main factors to consider for increasing mango fruit yields and quality. Our results indicate that cover cropping affects mango fruit yields and quality via alterations in soil fungal diversity, which bridges a critical gap in our understanding of the linkages between soil biodiversity and fruit quality in response to cover cropping in orchard ecosystems.

Plant diversity enhanced soil fungal diversity and microbial resistance to plant invasion

Interactions and feedbacks between aboveground and belowground biomes are fundamental in controlling ecosystem functions and stability. However, the relationship between plant diversity and soil microbial diversity is elusive. Moreover, it remains unknown whether plant diversity loss will deteriorate the stability of soil microbial communities. To shed light on these questions, we conducted a pot-based experiment to manipulate the plant richness gradient (1, 2, 4, 8 species) and plant (Symphyotrichum subulatum (Michx.) G.L.Nesom) invasion status. We found that, in the non-invasion treatment, soil fungal diversity significantly and positively correlated with plant diversity, while the relationship between bacterial and plant diversity was not significant. Under plant invasion, the coupling of plant-fungal alpha diversity relationship was enhanced, but the plant-fungal beta diversity relationship was decoupled. We also found significant positive relationships between plant diversity and soil microbial resistance. The observed positive relationships were determined by turnover (species substitution) and nestedness (species loss) processes for bacterial and fungal communities, respectively. Our study demonstrated that plant diversity enhanced soil fungal diversity and microbial resistance in response to plant invasion. This study expands our knowledge about the aboveground–belowground diversity relationship and diversity-stability relationship. Importance Our study newly showed plant invasion significantly altered relationships between aboveground and belowground diversity. Specifically, plant richness indirectly promoted soil fungal richness through the increase of soil TC without plant invasion, while plant richness had a direct positive effect on soil fungal richness under plant invasion. Our study highlights the plant diversity effect on soil fungal diversity especially under plant invasion, and the plant diversity effect on microbial resistance in response to plant invasion. These novel findings will add important knowledge about the aboveground–belowground diversity relationship and diversity-stability relationship.